In an asynchronous time division duplex (TDD) system, two stations separately use respective clock information. To implement synchronization of the two stations (such as a station A and a station B), the station A needs to extract a clock signal of a transmitter in the station B from a signal sent by the station B, and then the station A adjusts a clock signal of a receiver in the station A to be consistent with the clock signal of the transmitter in the station B.
In the prior art, the station B inserts a relatively long random signal into an initial position of a transmit timeslot, where the random signal carries no information and is used to help the station A complete clock signal synchronization. After the station A is switched to a receive timeslot, the station A recaptures and traces a clock signal (including a frequency and a phase) from a random signal received in an initial position of the receive timeslot, of the transmitter in the station B by using a clock recovery circuit including a phase-locked loop, and then the station A receives, by using the clock signal of the transmitter in the station B, a wanted signal sent by the station B.
However, in the prior art, a large quantity of random signals need to be inserted to enable the station A to acquire the phase of the clock signal of the transmitter in the station B. As a result, overheads are relatively high, and transmission efficiency is reduced.